1. Field of the Invention
The invention relates to a package structure and a manufacturing method thereof. More particularly, the invention relates to a package structure having superior heat dissipation and a manufacturing method thereof.
2. Description of Related Art
Chip packaging is performed to protect bare chips, lower the density of chip joints, and provide superior heat dissipation of chips. Conventional packaging methods include installing chips to a package substrate through wire bonding or flip chip bonding, so that the joints on the chips can be electrically connected to the package substrate. Therefore, the joint distribution of the chips can be re-distributed through the package substrate to satisfy the joint distribution of external devices of next hierarchy.
In terms of the conventional light emitting diode (LED) package structure, the LED chips need to be packaged before use and generate a large amount of heat energy when emitting lights. If the heat energy cannot be dissipated and is accumulated in the LED package structure, the temperature of the LED package structure increases continuously. Therefore, overheat may lead to brightness attenuation and shortened lifespan of LED chips or even permanent damage of LED chips under severe circumstances. The LED package structures adopted nowadays have heat sinks disposed therein for heat dissipation of LED chips.
The conventional package substrate is mainly constituted by multiple layers of patterned conductive layer and at least one insulation layer. The insulation layer is disposed between two adjacent patterned conductive layers for insulation. The heat sink is fixed on the lower surface of the package substrate through the adhesive layer. Generally, the LED chips are electrically connected to the package substrate. The heat generated by the LED chips is transferred to the heat sink for heat conduction through the patterned conductive layer and the insulation layer. However, since the adhesive layer and the insulation layer have low heat conductivity, the thermal resistance increases when the heat generated by the LED chips is transferred to the heat sink through the insulation layer and the adhesive layer, so as to result in ineffective heat conduction. Additionally, since the heat sink is adhered to the bottom surface of the package substrate through the adhesive layer, the thickness of the entire package structure cannot be reduced effectively. Thus, designers now focus on transferring the heat energy generated by LED chips to the external environment efficiently and reducing the thickness of the entire package structure in research and development.